A traditional handwritten screen is implemented by additionally providing a touch screen on a liquid crystal panel and needs a power supply to supply power continuously. On the one hand, charging is inconvenient under a specific use environment, which affects continuous use of the handwritten screen; on the other hand, by additionally providing the power supply, the handwritten screen has a large volume and a heavy weight, which is in the opposite direction of the current trend that devices are made lighter and handier, and leads to inconvenient use.